1. Field of the Invention
This invention relates to a solid state imaging device constituted by plural line sensors and, more particularly, to an intimate contact type solid state imaging device for forming an image of the equal size to the document size on the line sensor.
2. Description of the Prior Art
An intimate contact type image sensor, for forming an equimultiple size image as the document on a line sensor, is widely used in a facsimile or duplicator in that it can be reduced in size when assembled as compared with a reduced size optical system image sensor.
Meanwhile, since limitations are imposed on the longitudinal size of each line sensor, it is necessary with an intimate contact type image sensor to have a plurality of line sensors arrayed in the document scanning direction to provide a so-called multi-chip construction, with a view to reading wider documents.
As such a multi-chip type solid state imaging device, there are known a device of a so-called in-line type in which the line sensors are arrayed on a straight line, or a staggered type in which the line sensors are arrayed in alternate two rows. There is also known a technique, such as is shown in the Japanese Patent Publication Laid Open No. 61-126861, in which the ends of the line sensors are arrayed obliquely and the line sensors are arrayed in a straight line.
Meanwhile, in an in-line type solid state imaging device in which the line sensors are arrayed in a straight line, since there are lacking photodiodes of the line sensors at the joints between the line sensors, signal fluctuations at the joints present a problem.
In a so-called staggered array solid state imaging device, since the line sensor joints overlap, no problem in the joint occurs. However signal processing becomes complex since temporal shifting is produced by the two rows of the sensors and the enlargement and reduction by zooming or the like.
In the techniques shown by the above Patent Publication, the sensors are arrayed in a straight line. Similarly, positional accuracy at the ends presents a problem and assembling is not that easy.
As a technique for solving the above mentioned technical problem, the present Applicant has proposed an intimate contact type image sensor in the specification and drawings of the Japanese Patent Application No. 63-4943 which is an intimate contact type image sensor in which the light path is derived from an optical block to read straight type data.